Slightly less than half of the NYC to DC route and less than 25 percent of the NYC to Boston routes are on anything resembling dedicated rail.
Because of this, the occasional burst to higher speeds makes Acela only 18 to 20 minutes faster than the conventional diesel electric powered Northeast Regional on the NYC to Boston run.
The loss of dedicated rails in the 1960s and 1970s is why even Acela runs both of those routes slower than the steam engines of the 1940s.
The press release confirms the same sections of track tested this year saw high speed testing prior to Acela going operational years ago. At the time NIMBY protests over the noise levels of the fast trains kept them from ever going into service at those speeds.
http://www.amtrak.com/ccurl/623/361/Amtrak-to-Operate-Test-Trains-at-165-mph-ATK-12-084.pdfDedicated tracks are a must for HSR or regional rapid rail to succeed. The one caution is that unless you are in the remote desert southwest, you will have some NIMBY fights with abutters over the noise.
